We have a flower bed that has been sorely neglected. Elm seedlings and wild grapes have invaded. There are still some desirable plants - some Japanese dwarf iris that haven't bloomed for a couple of years and an antique rose that was very nearly choked out by elms, grape hyacinth, and some yellow-flowering bulbs that I haven't identified yet.
I have tried using vinegar and boiling water to kill off some of my elms. I use about 2 cups vinegar to gal of boiling water.
If you can dig up the flowers you want to save then till in the unwanted,good luck.